Code 33A: Map Sensor (Signal Volt Hi): Notes

The MAP sensor responds to changes in manifold vacuum. The ECM receives a signal voltage from MAP sensor varying from .5-2.0 volts at idle closed throttle) to 4-5 volts at wide open throttle. If MAP sensor fails, ECM will substitute a fixed MAP value and use the TPS input to control fuel delivery.

1. This determines if Code 33A is the result of a hard failure or an intermittent condition. Code 33A will set if:
   • MAP signal indicates low vacuum.
   • No Code 21A or 21B is set.
   • TPS is less than 5 percent.
   • Conditions are present for more than 5 seconds.
2. This step simulates conditions for a Code 33B. If ECM recognizes the change, the ECM and circuits No.416 and 432 are okay. If circuit No. 452 is open, Code 21A may be stored.